The present invention relates to electro-optical mouses and relates more particularly to an electro-optical mouse which includes a light source to project light on a grid of lines on a reflective surface, a cylindrical lens to amplify the reflected image and send amplified signals corresponding to X-lines to a first detector and amplified signals corresponding to Y-lines to a second detector, and a microprocessor for processing, corresponding signals from said first and second detectors control the movement of a cursor associated with a visual display system.
Conventionally, a mouse which is used to move or position the cursor or part of the display of a computer system is generally operated through mechanical transmission. It is generally comprised of a rolling ball disposed at the bottom and driven to rotate in a direction and amount corresponding to movement of a joy-stick and therefore, convert translational motion into a position signal for controlling the movement of the cursor or part of the display in a computer system. The main disadvantage of the mechanical mouse is its high error rate. Further, the rolling ball may wear off easily causing severe error.
Recently, electro-optical technology has been applied in manufacturing electro-optical mouses for controlling the movement of the cursor in a visual display more efficiently and accurately. An electro-optical mouse generally comprises at least one light source to project light on a grid of lines on a reflective surface and at least one detector for interpreting the position of the housing thereof over the grid of lines. Translational motion of the housing is further converted into a position signal by a transducer for controlling the movement of the cursor.
According to the known structures of electro-optical mouses, a single lens and a single detector may be used to detect light changes in X and Y directions through two ways. In a first way, the lines on the grid are made with optically transmissive inks and are illuminated by a dual color monochromatic light source so that the moving direction of the housing can be effectively distinguished by the detector according to the wavelength of the reflected light. In a second way, the X and Y directions,are detected through different lenses, namely, the X lines are made on the top edge of the reflective surface while the Y lines are made on the bottom edge thereof and, separate lenses are provided at different focal distances for detecting the reflection from the X lines and the Y lines separately. In the electro-optical mouses which utilize a single lens and single detector for X and Y detection, the line crossings in the X direction may interfere with the line crossings in the Y direction to affect the accurate control of a cursor. The present invention is to utilize cylindrical lenses to amplify line crossings in the X and Y directions separately so that the changes contrast ratio can be more effectively sensed by the detectors and interference problems between X and Y line crossings can be eliminated.